不須透過迴圈，直接將Array專為List

using System;
using System.Collections.Generic;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] s = { "a", "b", "c", "d", "e" };
            List<string> l = new List<string>(s);
            Console.WriteLine(String.Join(",", l.ToArray()));
        }
    }
}